gistfile1.m

UIView * viewRoot = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 480, 320)];
viewRoot.backgroundColor = [UIColor clearColor];
UIView * view1 = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
UIView * view2 = [[UIView alloc] initWithFrame:CGRectMake(480-100, 0, 100, 100)];
UIView * view3 = [[UIView alloc] initWithFrame:CGRectMake(0, 320-100, 100, 100)];
UIView * view4 = [[UIView alloc] initWithFrame:CGRectMake(480-100, 320-100, 100, 100)];
[viewRoot addSubvier:view1];
[viewRoot addSubvier:view2];
[viewRoot addSubvier:view3];
[viewRoot addSubvier:view4];